Federal

Glow Plug Relay Control - Federal






The Glow Plug (GP) Relay Control is used to energize the glow plugs for assisting cold engine start-up. Engine Oil Temperature, battery positive voltage (B+), and Barometric Pressure (BARO) are used by the PCM to calculate glow plug on-time and the length of the duty cycle. On-time normally varies between 1 and 120 seconds. With colder oil temperatures and lower barometric pressures, the plugs are on longer. If battery voltage is abnormally high, the duty cycle is shortened to extend plug life. (The glow plug relay will only cycle on and off repeatedly when there is a system high voltage condition greater than 16 volts.)

An open in the glow plug relay circuit will render the glow plugs inoperative. A short circuit will result in a glow plug's always ON condition.